Efficient utilization of biomass for the sustainable production of chemicals and energy is an important way to reduce dependence on fossil resources, which helps in the containment of CO2 emissions. Hence, researchers are focusing on technologies that can facilitate the conversion of renewable biomass into fuels and chemicals. Moreover, future economic and industrial growth of a nation depends upon its ability to utilize locally available sustainable feedstock (biomass) for fuel and chemical production. Hence, there is a need to shift from traditional petrochemical feedstock towards biomass based feedstock that preserves ecology as well as leads to economic gains of a nation (C. H. Christensen et al., ChemSusChem 2008, 1, 283)
HMF is a biomass/cellulose derived component, obtained without fermentation, thus it is a potential “carbon-neutral” feedstock for fuels and chemicals. HMF on selective oxidation gives corresponding dicarboxylic acid, wherein HMFCA (5-hydroxymethyl-2-furancarboxylic acid) is formed on oxidation of HMF, which is gradually converted to FDCA, a more stable product.
Bearing in mind the utilisation of biomass as a primary substrate, several sustainable feedstocks have been suggested. Hexoses are abundant monosaccharides existing in nature. Selective dehydration of hexoses gives a potential platform chemical called 5-hydroxymethylfurfural (HMF). Under specific reaction conditions, HMF can be oxidized to yield 2,5-furandicarboxylic acid (FDCA), which is a valuable chemical intermediate. US DOE biomass program has identified FDCA as one of the 12 important chemicals derived from biomass that can be used as a chemical building block in future. It is a potential replacement source of terephthalic acid; the monomer is currently used for the production of polyethylene terephthalate (PET) and derived from hydrocarbon sources.
A number of different homogeneous and heterogeneous catalyst systems have previously been reported for the selective oxidation of HMF to FDCA. Use of stoichiometric oxidant KMnO4 and industrially practiced catalyst Co/Mn/Br were also reported. Direct synthesis from fructose has been attempted using a solid acid and Pt/Bi/C in water/Methyl isobutene Ketone, yielding 25% FDCA with 50% selectivity. Furthermore Ribeiro et. al, obtained 71% yield of FDCA using silica-encapsulated cobalt acetylacetonate as a bifunctional acid-redox catalyst at 160° C. (Catal. Commun. 2003, 4, 83)
Lilga et al. have reported an industrially promising method to oxidize HMF to FDCA in up to 98% yield at 100° C. and 1 MPa oxygen pressure using a Pt/ZrO2 catalyst (US Patent 20080103318, 2008). Gorbanev et al. demonstrated that Au/TiO2 could oxidize HMF into FDCA in 71% yield at room temperature (ChemSusChem 2009, 2, 672). Corma and co-workers have showed that Au/CeO2 was found to be more selective for FDCA (ChemSusChem, 2009, 2, 113). Pasini et al. obtained high yield of FDCA from HMF using supported Au—Cu nano particles as catalyst (Green Chem 2011, 13, 2091). Villa et al. showed that Pd-modified Au on Carbon as an effective catalyst for the FDCA production from HMF (ChemSusChem 2013, 6, 60). Oxidation of 5-hydroxymethylfurfural over supported Pt, Pd and Au catalysts such as Pt/C, Pd/C Au/C and Au/TiO2 reported.
Although some of the above reported processes produce high yields of FDCA, usage of homogeneous base (1-20 equiv. NaOH) and high oxygen pressure (10-20 bar) makes them difficult to scale up. In order to make the process free of corrosive base, researchers have conducted the above reaction without base. Gupta et al. have reported hydrotalcite-supported gold-nanoparticles as a base free catalyst for HMF oxidation which produce 99% yield of FDCA (Green Chem., 2011, 13, 824). Recyclability of the above catalyst is an issue due to the Leaching of OH− and HCO3− groups after reaction from the support. Riisager and his co-workers have worked over spinel supported Ru catalyst, but the yield of FDCA was not good enough for scale up (Top Catal (2011) 54, 1318). Aerobic oxidation of HMF to FDCA with ruthenium containing ferrite-spinel catalyst is demonstrated by Ester Eyjolfsdottir et al. However, the process is time consuming to get good yield of FDCA.
U.S. Pat. No. 5,523,509 and U.S. Pat. No. 5,702,674 (Oyoung, Chi-lin et al.) described OMS-1 tunnel-substituted with a metal cation selected from the group consisting of Li, Na, K, Cs, Mg, Ca, Ba, Co, Ni, Cu and Zn. Selective oxidation of alcohols using octahedral molecular sieves was demonstrated by Young-Chan Son et al., in U.S. Pat. No. 6,486,357.
Manganese oxides with tunnel structures exhibiting molecular sieving properties are referred to as manganese oxide octahedral molecular sieves (OMS). They include synthetic todorokite (OMS-1) and cryptomelane (OMS-2). Manganese oxide octahedra (MnO6) are the basic structural units of OMS materials that combine to form tunnels by linkages at their edges and vertexes. OMS-1 utilizes three MnO6 octahedra on each side to form a 3×3 square tunnel with a pore size of about 6.9 Å. Similarly, OMS-2 has a 2×2 square tunnels with pore size of about 4.6 Å. Inside the tunnel of these OMS structures, K (cryptomelane) or Mg (todorokite) ions are present as exchangeable cations. Hui Huang et al., describes a facile single-step method developed for synthesizing todorokite-type manganese oxide octahedral molecular sieves (OMS-1) (Chem. Commun., 2010, 46, 5945).
In view of above prior art, metal catalysts employed in the synthesis of FDCA accompany technical constrains such as lack of recyclability due to Leaching of metal support, time consuming process, poor yield of the product, necessity of base, industrial feasibility. This creates the need of alternative stable, cost-effective and recyclable catalyst which obviates requirement of base to produce high yield of FDCA in short period of time.
There are only a few reports on the selective oxidation of HMF to FDCA in the absence of base. Even in case of reported catalysts that have both basic component and redox center, they lack recyclability. Leaching of the basic active center makes the process difficult to recycle.
To overcome the short comings of the prior art, the present inventors have developed alternative, cost-effective, recyclable catalyst composition comprising metal loaded or exchanged alkali or alkaline earth metal oxide octahedral molecular sieves; having both redox and basic sites, as the basic sites are part of the structure and does not leach out during the reaction and also obtained in very good yields of FDCA within short span of reaction time. Further the said catalyst is highly active for selective oxidation of HMF to obtain FDCA in high yield and selectivity in short reaction time.
Gluconic acid (GA) is a mild organic acid which is an important chelating agent with many applications in the chemical industry. Major part of its production is used in food industry. It is also used in pulp and paper manufacturing, water treatment and in the pharmaceutical industry. Around the globe, it is produced to the tune of 100,000 tonne per annum. Gluconic acid can be manufactured in different ways, viz., chemical, electrochemical, biochemical and bioelectrochemical. But, majority of its production is carried out through fermentation process in which enzymes like Aspergillus niger and Gluconobacter suboxydons oxidizes glucose. The main obstacle to the large-scale application of the fermentation processes is that it requires neutralization of the acid in order to avoid deactivation of the enzymes.

Oxidation of glucose to gluconic acid over noble metal catalysts, including Pt, Pd and Au, has been reported extensively. Gold catalysts show superior activity and selectivity to gluconic acid when compared to other precious metals such as Pd or Pt. Baatz et al. attributed superior performance of Au to its resistivity to poisoning and overoxidation (J. Catal., 2002, 206, 242-247). Biella and co-workers used Au supported on activated carbon in the pH range of 7.0 to 9.5 for glucose oxidation. They found that Au particles tend to agglomerate after the reaction. If metal oxides (Al2O3, TiO2) are used as support, Au can resist sintering and agglomeration compared to the carbon supports.
Recently Leshkov's group reported base free oxidation of glucose to gluconic acid using CeO2 as support. but, most of the reports suggest that this reaction is best conducted by adding an external base to maintain pH in 7.5-12 range. Since, most of the work was conducted using acidic or neutral catalyst supports, it was necessary to add an external base. It is well known that gold particles tend to sinter at high pH during the reaction. Hence, it is recommended that the reaction is best conducted in the absence of a base. We have carried out oxidation of glucose using precious metal supported on a microporous material with basic properties. Since, the alkaline earth metal in the support has basic property; it can donate electrons to Au to keep it in reduced state, leading to stable activity of the catalyst.
2-Furoic acid (FA) is an important intermediate, which is mainly obtained by oxidation of furfural. It is widely used as a preservative and flavouring agent. It is also used as a non linear optical material and also in the preparation of nylon. Commercial production of FA is conducted through microbial route using organism called Nocardia coralline. 
Oxidation of furfural to FA was studied with different homogeneous catalysts, MnO2, KMnO4 and NaOCl. since these processes use stoichiometric quantities of these reagents; their disposal is an environmental issue. Heterogeneous catalysts like Ag2O mixture of metallic oxides like Cu, Fe were also reported for the oxidation of furfural. Verdeguer et. al. used lead/platinum on charcoal as catalyst for the above reaction. In all these processes, base is used as promoter (Applied Catalysis A: General, 1994, 112). Disposal of base is tedious and there are environmental issues associated with it. Till today, there were no reports on base free process for the above reaction. However, we have conducted furfural oxidation without addition of external base.